The Use of Measuring Instruments, Accuracy, Consistency, Sensitivity and Errors

 
1.4 The Use of Measuring Instruments, Accuracy, Consistency, Sensitivity and Errors
 
Measuring Length
 
Definition
Length is the distance between two points.
 
  • Can be measured in millimetres (mm), centimetres (cm) or kilometres (km).
  • Can be measured using Vernier calipers where it can measure the thickness of outer diameter, inner diameter and depth of an object.
  • Vernier calipers is more accurate compared to a ruler
 
 
  • Systematic error - caused by using measuring instruments that are no accurate
  • Example: Zero error can be determined when the jaws of the vernier calipers are closed.
 
 

To obtain the actual reading, zero error has to be taken into consideration.

Actual reading = Reading of vernier calipers - zero error

 
Measuring Mass
 
Definition
Mass is the quantity of matter in it
 
  • Mass can be measured using digital electronic balance accurately and precisely
 
Measuring Time
 
Definition
Length is the distance between two points.
 
  • Time can be measured using stopwatch accurately to 0.01 seecond
 
Measuring Temperature
 
Definition
Temperature is the degree of heat of an object
 
  • A digital thermometer can give accurate reading of temperature up to \(0.1^\circ\text{C}\)
 
Measuring Electric Current
 
  • Ammeter is used to measure electric current in a circuit
  • A digital ammeter gives more accurate and precise readings with accuracy up to 0.01A.
 
Measuring Volume of Water
 
  • A measuring cylinder can measure the volume of water
  • Parallex error occurs when the reader's eyes are not peperndicular to the reading scale
 
 
How to minimise systematic errors and random errors:
 
Systematic Errors
  • Zero error
  • Inaccurate measuring instrument
Ways to ovecome
  • Conduct experiments with caution
  • Repeat experiment using different measuring instruments

 

Random Errors
  • Parallax error
  • Carelessness of observer when taking the reading
  • Wrong technique
Ways to ovecome
  • Take a few readings of measurement and take the average reading
  • To reduce impact of parallax error, observer eyes should be perpendicular to the scale reading

 

The Use of Measuring Instruments, Accuracy, Consistency, Sensitivity and Errors

 
1.4 The Use of Measuring Instruments, Accuracy, Consistency, Sensitivity and Errors
 
Measuring Length
 
Definition
Length is the distance between two points.
 
  • Can be measured in millimetres (mm), centimetres (cm) or kilometres (km).
  • Can be measured using Vernier calipers where it can measure the thickness of outer diameter, inner diameter and depth of an object.
  • Vernier calipers is more accurate compared to a ruler
 
 
  • Systematic error - caused by using measuring instruments that are no accurate
  • Example: Zero error can be determined when the jaws of the vernier calipers are closed.
 
 

To obtain the actual reading, zero error has to be taken into consideration.

Actual reading = Reading of vernier calipers - zero error

 
Measuring Mass
 
Definition
Mass is the quantity of matter in it
 
  • Mass can be measured using digital electronic balance accurately and precisely
 
Measuring Time
 
Definition
Length is the distance between two points.
 
  • Time can be measured using stopwatch accurately to 0.01 seecond
 
Measuring Temperature
 
Definition
Temperature is the degree of heat of an object
 
  • A digital thermometer can give accurate reading of temperature up to \(0.1^\circ\text{C}\)
 
Measuring Electric Current
 
  • Ammeter is used to measure electric current in a circuit
  • A digital ammeter gives more accurate and precise readings with accuracy up to 0.01A.
 
Measuring Volume of Water
 
  • A measuring cylinder can measure the volume of water
  • Parallex error occurs when the reader's eyes are not peperndicular to the reading scale
 
 
How to minimise systematic errors and random errors:
 
Systematic Errors
  • Zero error
  • Inaccurate measuring instrument
Ways to ovecome
  • Conduct experiments with caution
  • Repeat experiment using different measuring instruments

 

Random Errors
  • Parallax error
  • Carelessness of observer when taking the reading
  • Wrong technique
Ways to ovecome
  • Take a few readings of measurement and take the average reading
  • To reduce impact of parallax error, observer eyes should be perpendicular to the scale reading